Apparatus method of geophysical exploration

ABSTRACT

The invention comprises a detonator lowered into water and housing a succession of explosions for emanating energy waves to pass downwardly into the earth and includes a barrel and sequentially fuel and combustion-supporting gas which are ignited, the explosion creating pressure to open a foot valve to pass therebelow, the valve seat being yieldably urged seated upwardly, a purge valve then admitting purge gas into the barrel to urge the residual burnt products through bleed passage means to condition the barrel for a successive explosion.

United States Patent Inventor William P. Holloway 1404 E. 5th Ave., Austin, Tex. 78702 App]. No. 842,814 Filed July 7, 1969 Patented Nov. 30, 1971 Continuation-impart of application Ser. No. 394,358, Sept. 3, 1964, and a continuationin-part of 504,529, Oct. 24, 1965, now abandoned. This application July 7, 1969, Ser. No. 842,814

APPARATUS METHOD OF GEOPHYSICAL EXPLORATION 7 Claims, 15 Drawing Figs.

US. Cl 181/.5 NC, l8l/.5 AG, 181/.5 ED Int. Cl G0lv 1/00 Field of Search 181/.5

anus/v55 DEVELOPMEN T P comm/amen SURVEYOR 23,552 e ii-A; 26 N LINE References Cited UNITED STATES PATENTS 2,846,019 8/1958 Lang 18 H5 2,994,397 8/l96l Huckabay l8 l/.5 3,256,501 6/1966 Smith 181/.5 3,289,784 12/1966 Cassand et al. l8 l/r5 Primary Examiner-Rodney D. Bennett, Jr. Assislanl Examiner.l0scph G. Baxter ABSTRACT: The invention comprises a detonator lowered into water and housing a succession of explosions for emanating energy waves to pass downwardly into the earth and includes a barrel and sequentially fuel and combustion-supporting gas which are ignited. the explosion creating pressure to open a foot valve to pass therebelow, the valve seat being yieldably urged seated upwardly. a purge valve then admitting purge gas into the barrel to urge the residual burnt products through bleed passage means to condition the barrel for a successive explosion.

PATENTEDHUV 30 IBTI 3,623 570 SHEET 2 OF 5 SOLENOID OPE RA TED SOLENOID OPERA TED Q METER/N6 VAL VE METER/N6 48 ATTORNEY PATENTEDuuv 30 ISH SHEET 0F 5 I 7 i .1. U WILL/AM P l-loLLam/A A T TORNE Y PAIENTEDunv 30 I97! 3. 623 570 SHEEI 5 UF 5 WILLIAM F HOLLOWAY ATTORNEY APPARATUS METHOD OF GEOPHYSICAL EXPLORATION This application is a continuation-in-part of copending application Ser. No. 394,358, filed Sept. 3, 1964, and also being a continuation-in-part of once copending application Ser. No. 504,529, filed Oct. 24, 1965, now abandoned; both for AP- PARATUS AND METHOD OF GEOPHYSICAL EX- PLORATION.

This invention relates to geophysical exploration apparatus of the type where an explosion is set up to propagate vibrations to pass downwardly into the earth, the explosion being controlled in manner that it does not disrupt the elasticity of the bored hole which is sealed off to contain the explosion.

It is consequently a prime object of this invention to provide apparatus for setting motion vibration or sound waves which pass down into the earth from a bore where a controlled explosion takes place in manner that the waves are propagated in smooth patterns not calculated to disrupt the elasticity of the bored hole.

It is also an important object of this invention to provide geophysical exploration apparatus of this class which require receiving the vibrations, as reflected back to the earth's surface, in manner that these vibrations are reflected back up wardly to encased geophones with substantially wide bases of reception whereby the vibrations are unimpeded by extraneous noises as may ordinarily occur in the weather zone just under the earth surface or in the space just above the surface.

It is also another important object of this invention to provide exploration apparatus which pennit a wide area of control of the quality and characteristics of detonations obtained so that the apparatus and usages may be employed in a wide range of soils, terrain, weather conditions, and to be effective at varying depths and in various fonnations.

It is also another important object of this invention to provide exploration apparatus of this class whereby the holes used for containing the novel types of explosions employed may be drilled with conventional drilling equipment.

It is also another important object of this invention to provide apparatus of this class whereby the recorded vibrations are more readily interpreted than those recorded by conventional apparatus.

It is also an important object of the invention to provide apparatus by which the depth of exploration can be varied by the volume of charge set off in the bored hole and thus a smooth comparison can be made by the smoothly arriving vibration pattern from different depths.

It is another and further object of the invention to provide apparatus of this class by which a plurality of charges in closely spaced together bored holes may be discharged simultaneously thereby to obtain a summation pattern of wave reflection at each of variously arranged geophone cases.

It is also another particular object of this invention to provide apparatus whereby to detonate a plurality of charges at predetermined spaced apart time intervals so that the resulting summation of the returned or reflected vibration waves is intensifled as to amplitude.

The improved invention also has a primary and most important object of providing a detonating gun or explosion barrel which, upon detonation, builds up the force of explosion against a valve in the lower end thereof; the explosion, upon unseating such valve, being deflected in manner to be ricocheted downwardly with directed effect.

Also, the improved invention has an additional and important object of providing a detonating gun or explosion barrel of this class in which the fuel and oxygen are metered at predetermined pressures into a closed explosion chamber of predetermined volume to exert force of predetermined amount to unseat a control valve at the bottom of the explosion chamber whereby the excess of generated force, above that required to unseat the control valve, is deflected to be ricocheted downwardly with directed effect.

Additionally, the improved invention has an additional and important object of providing a firing box by which the fuel and oxygen conduits may be opened to control a predetermined mixing interval in the explosion barrel, by which the mixture may be detonated after the mixing interval, and by which the explosion barrel may be vented upwardly through the top of the gun.

The improved invention has another and essential object of providing a detonating barrel or gun of this class which may be equipped with packer means to position it in a borehole in the ground, and which requires no such packer means when lowered to be detonated below the surface of the water.

The improved invention has still a further and important object of providing, in a detonating barrel or gun of this class, a control valve and deflector at the bottom of the explosion chamber or barrel, whereby the degree of taper of the valve seat and the inner diameter and length of the deflector bear substantially critical relationship to the quality of vibration waves set in motion below the deflector.

Also, the improved invention has still another and vital object of providing a detonating barrel or gun of this class in which the venting of the explosion chamber after a detonation bears a timed relationship to the ignition of the mixture within the chamber.

It is also another primary object of this invention to provide a source for emanating sonic waves or vibrations to be directed into the earth from a detonation means in water in manner that such vibrations, emanated from a single location, may provide a reflected record comparably interpretive with records emanated from conventional dynamite charges from a plurality of bores to provide a single record.

It is still another and important object of this invention to provide a source for emanating sonic waves or vibrations of this class to be directed into the earth from a bored hole into the earth and containing water up to a predetermined level with relation to the source or blast gun, the blast gun being disposed in the bored hole short of the bottom thereof.

It is yet another object of this invention to provide a source for emanating sonic waves or vibrations of this class to be directed into the earth from a position of immersion in a body of water, as the ocean or sea, or a lake or river, no bored hole being required.

It is still a further object of this invention to provide a source for emanating sonic waves or-vibrations of this class to be directed into the earth, as a blast gun, which is purged after each blast by the timely injection of a purging gas, as compressed air, to force the unexhausted gases from the detonation chamber through bleed passage means in the relief valve.

It is yet another object of the invention to provide a source of emanating sonic waves or vibrations of this class to be directed into the earth with the steps of charging with a fuel and a combustion supporting gas, detonating the charge, and purging products of combustion from the blast chamber are controlled to occur successively over predetermined time intervals.

Other and further objects will be apparent when the specification herein is considered in connection with the drawings, in which:

FIG. I is a generally discursive view of a geophysical operation, part in perspective and part in sectional elevation, which shows apparatus conventionally employed together with apparatus particularly included by this invention;

FIG. 2 is a sectional elevation of a detonator and hole sealer in a bored hole, and which demonstrates one form of apparatus employed by this invention;

FIG. 3 is an overhead plan view taken along line 33 of FIG. 2;

FIG. 4 is a sectional bottom view taken along line 4-4 of FIG. 2;

FIG. 5 is a sectional elevation view of a geophone case comprising a preferred form of invention;

FIG. 6 is an overhead plan view taken along line 6-6 of FIG. 5;

FIG. 7 is a sectional bottom view taken along line 7-7 of FIG. 5;

FIG. 8 is a fragmentary sectional elevational view to be added under certain conditions below the structures shown in FIG. 2;

FIG. 9 is a view, part in sectional elevation, and partially diagrammatic, showing another embodiment of the "gun or explosion barrel, together with the firing box, wiring, and valving employed to operate the gun;

FIG. 10 is a sectional elevation through the valve and deflector at the lower end of the explosion barrel shown in FIG. 9;

FIG. 11 is a small scale view of the gun shown in FIGS. 9 and 10, showing proportions, and appearance as readied to be lowered for detonation below the water;

FIG. 12 is a view, part in sectional elevation, diagrammatic, showing a preferred embodiment of blast gun, together with firing box, wiring, and valving, the gun requiring no sealing means and vent, but rather a bleed passage through the relief valve to purge the gun chamber each time promptly after discharge;

FIG. 13 is a small scale view of the gun shown in FIG. 12, with elements in relative disposition, as readied to be lowered into water, either in a bored hole, or into a body of water;

FIG. 14 is a plotted record, for comparison with conventional records, of traces from alternate geophones which have received seismic waves emanated from a single blast from a single-blast gun of the type shown in FIG. 12; and

FIG. 15 is a plotted record, for comparison with conventional records, of traces from alternate geophones which have received seismic waves emanated from a succession of blasts from a single-blast gun ofthe type shown in FIG. 12.

Referring now in detail to the drawings in which like reference numerals are assigned to like elements in the various views, FIG. 1 sets out in full pictorial and graphic view the various novel equipment employed in relation to conventional apparatus usually employed. In the course of setting up geophysical operation a surveyor l0 and rodman 11, as shown in FIG. 1, are laying out a survey of a location and the first thing that they locate are shot points or points where boreholes are to be drilled. In FIG. 1, a drilling rig 12 is shown as having drilled a first bored hole 13, a second bored hole 14, and a third bored hole 15, the rig 12 being shown still in location at the bored hole 15.

The apparatus by which the hole is drilled, being conventional, is not described herein in detail, a conventional truck 16 being provided and carrying thereon the usual power takeoff for rotating the drill stem and bit. Also, since it is necessary to lubricate the drill bored, water or drilling mud is supplied from a water truck 17, being shown adjacent the drilling rig 12.

After a drilled bore has been located the present invention shows an alignment of geophone casings 19 which are spaced equal distances apart and along a radial line from the bored hole 13. As viewed from above, there would probably be four or six such lines of geophone cases equally angularly spaced apart from the vertical axis of the bored spaced apart successively from one another. Also, in each line, the innermost geophone case 19 would be located an equal distance from the aforesaid vertical axis.

From each geophone case 19, an electrical cable 20 leads to an instrument truck 21 to be connected into the recording compartment 22 thereof where recordings of reflected waves as sound are made in conventional manner. From the record ing compartment 22 records obtained may be observed on a roll by recorder 23 who sits in the developing compartment 24 of the truck and studies the records as to amplitude, frequency, wave shape, pattern, and other information to be obtained therefrom. The reels of wire as for the cables 20 and telephone lines 26 have been brought to the field on a wire truck 25.

In the invention shown an explosion truck '27 carries thereon the explosive fuel, as for instance, a drum of propane 28. Also, a drum of oxygen 29 is shown on the explosive truck 27, and also a compressor 30 which discharges into a header 31 from which compressed air is delivered through pipes 32 to and partially hole 13, and equally seal the bores 13, I4, and 15 in cooperation with detonators 33 to be hereinbelow described in detail.

Referring now in detail to FIG. 2, a detonator 33 is shown comprised of a steel pipe 34 as its body or frame element. Then the detonator 33 is surrounded by neoprene sleeves 35 which extend vertically in end to end relationship along the pipe 34.

A series of pipes 32 of relatively small diameter extend one from each space 37 in each sleeve 35 upwardly within the pipe 34 and through a cap 38 which closes the top of the body, housing or pipe 34. Outwardly of the cap 38 the small pipes 32 connect into the aforesaid header 31 which in turn receives compressed air from a compressor 30 on the back end of the explosion truck 27. In addition to the pipes 32 an igniter 40 extends downwardly through the cap 38 and downwardly through a closure plate 41 which is provided just slightly above the bottom of the pipe 34. The igniter 40 extends to an ignition box 42 which is operated by an explosion engineer 43 who is shown in FIG. 1 in position just to the rear of the truck 27.

In addition to the igniter 40 a vertical pipe 36 extends downwardly through the cap 38 and through the bottom closure plate 41 and terminates in an upwardly urged seated check valve 44 shown diagrammatically in FIG. 2; this vertical pipe 36 having a flexible conduit 45' connected to its upper end to extend to the propane tank 28 on the explosive truck 27.

Additionally, a vertical pipe 36 extends downwardly through the cap 38 and through the bottom closure plate 41 and terminates in an upwardly urged seated check valve 47, the upper end of the pipe 36 above the cap 38 being connected by means of a flexible conduit 48 to the aforesaid oxygen bottle 29 on the explosion truck 27.

The construction and contents of the geophone cases 19 are shown in FIGS. 5-7, inclusive, and each case 19 is constructed in the following manner. The housing of the casing is comprised preferably ofa light metal, as aluminum, and consists of a hollow, frustoconical shell 50 with closed top and open base with an eyebolt 51 threaded centrally into the underside of the top closure 52 from which hangs downwardly a soft lay, small diameter, flexible steel cable 53, with a conventional sleeve or clamp 54, termed a stakon" clamp, being installed thereon to anchor the upper end of the cable. Also the lower end of the cable 53 is connected to an eyebolt 51 by means of a corresponding clamp 54.

A round disk or suspension plate 55, having its peripheral edge beveled substantially parallel with the inner surface of the housing 50, is provided, and in final assembly, as will be hereinbelow described, the shank of the lower eyebolt is passed through a central bore in the plate 55, and final assembly of eyebolt and plate is accomplished by a lockwasher and nut 57 being tightened upon the end of the eyebolt shank, as shown in FIG. 5.

A rubber gasket 58, or other suitable buffer material is installed as a liner within the lower inner surface of the housing or casing 50, and extends upwardly from the base to a height above the top of the plate 55. Also a circular bubble level 59 is installed centrally on top of the top closure plate 52, as best seen in FIG. 6, and four eyebolts 51 upstand from diametrically opposed outer edges of the top closure plate 52 to which are tied sashcord 60 to provide a handle for each case 19.

Suitable bores and counterbores 61 are made upwardly through the underside of the plate 55, as indicated in FIG. 7, the heads of the bolts which fit into the counterbores falling into recesses thus provided and not being shown in FIG. 5. These bolts, not shown, are of the type to connect upwardly, each into a conventional geophone 62. The geophones 62 are shown as four in dotted lines in FIG. 7, with three being visible in FIG. 5. However, although this number is shown for clarity, a greater number may be provided, such as six or eight. As indicated by the boltholes 61 in FIG. 7, for the best results the geophones are equally angularly and radially spaced from the vertical centerline of the plate 55.

The geophones are of the conventional type, one of which is conventionally installed at each of aligned stations which begin along each line of stations at substantially the same radical distance from a shothole in conventional geophysical exploration, with each successive geophone in a line being spaced equally radially apart outwardly from the initial station in a line.

As conventionally constructed, geophones are comprised of small, sensitive coils which move small magnets responsive to the vibrations imparted thereto. In the case of geophysical exploration, vibrations are set forth to move downwardly, as by dynamite detonated at the bottom of a shothole, with only a portion of the energy liberated by the dynamite going into the propagation of sound waves or vibrations downwardly. Then, such sound waves as move downwardly may strike a reflecting layer in the earth, with the result that waves are reflected back upwardly. These returning or reflected vibrations affect movement of the sensitive coils, and are thereby translated into electrically generated impulses to be transmitted from the geophones to oscillographs.

These geophones, as indicated, are in proportional size to the Hall-Sears" phones conventionally used, and transmit the waves in terms of electrical impulses to conventional recording apparatus in an instrument truck 21, as shown in FIG. 1. However, it should be especially noted, when considering FIG. 1 in connection with the geophone cases 19 indicated thereon, that a geophone case 19, containing several geophones 62 is provided at each station, whereas in conventional geophysical exploration, a single geophone is provided at each station, and generally embedded slightly in the ground.

The geophones 62 are series connected by small radio-type hookup wires 64 with the wires from the last geophone in the series leading out through a conventional Jones connector" 63 to an insulated conductor cable 20 which extends and makes appropriate connection into the instrumentation in the recording compartment 22 of the instrument truck 21 in FIG. I.

When the wires from the last geophone of a series in a case 19 have been extended through a Jones connector" or suitable sleeve insert through the housing wall, the suspension plate 55 can be connected for suspension by installing the lower eyebolt shank through the plate 55, as aforesaid, and installing the lockwasher and nut 57 thereon.

Then a baseplate 65 is ready to be assembled to the base rim of the housing, casing, or shell 50, suitable flathead machine screws 66 being used for this purpose, four pairs being preferable and diametrically disposed, as indicated in FIG. 5, and equally angularly spaced apart.

The refinements in operation included by this invention reside in the fact that the blast may be controlled so as not to rupture the elastic limit of the soil in which the holes are bored, as the holes 13, 14, and shown in FIG. 1, whereby the sound waves travel downwardly with greater effectiveness and efi'lciency, and without loss of that part of the force of explosion normally expended by the dynamite conventionally used in shattering the adjacent formation in order to set vibration waves in motion, which, being emanated in all directions, are only in part directed down into the earth, as desired.

The tubes or small diameter pipes 32, one of which passes to each space 37 within a sleeve 35, may pass upwardly to a header 3], located immediately above each pipe cap 38, as shown in FIG. 2, or such may pass through extensions 32 from the pipes 32 within a detonator 33, to a service header 31 adjacent the explosives truck 27 which carries a source of compressed air, as a compressor 30. In either case, a valve 67, (shown in FIGS. 2 and 3, and included by the header 31 in FIG. 1), controls the admission of compressed air into the header 31 from which it passes down into the detonator 33 and out into each respective sleeve 35 to expand the sleeve to the bored hole, as the bored hole 13 in FIG. 2.

The force of the compressed air should be sufficient to billow out each sleeve 35, as shown in FIG. 2, until it positively seals against the wall of a bored hole 13, whereas the points of adjacency, overlap or junction 69 of the end to end junctions between sleeves are so firmly bound to the pipe or housing 34 that they are not ruptured by the inflating force applied by the compressed air to the sleeves 35.

The sleeves 35 thus act as oil well packers and seal against the formation, the arcuate areas of contact 68 being exaggerated in degree in FIG. 2, but in any event the seal is sufficiently urged to urge the successive sleeves 35 to press against the bored hole in manner to cause a degree of indentation by the sleeves 35 being urged into the bored hole wall. Thus, when an explosion may be set off below the detonator 33, the successive sleeves act as dams to offer increasing resistance to the forces of explosion. Thus, if a lower surface of connection 69 is ruptured by an explosion therebelow it should take a greater force to rupture the connection 69 thereabove. Thus the force of explosion or detonating force, if it ruptures one connection surface 69, should be opposed by a successively greater force of resistance at the next connection surface 69 thereabove. This can occur inherently, as the compressed air will arrive at spaces 37 from top to bottom, in succession, or a pressure differential may be applied, as by turning off valves, not shown, in succession, controlling the pipes 32, from bottom to top.

A combination of gases found most advantageous for the creation of an explosive force, would comprise a mixture of approximately 10 percent propane and 60 percent oxygen, with the remaining gas being supplied by the air inherently in the bottom of the bored hole.

As shown in FIG. 1, the pipes 45', 48 from the respective vertical pipes 45, 36 within the detonator 33, extend respectively to the propane drum 28 and to the compressed-oxygen tank 29, both on the explosives truck 27.

A solenoid-controlled metering valve 70 is provided at the top of the propane pipe 45, and from which extends the flexible conduit 45' to the compressed-propane drum 28; also, a solenoid-controlled metering valve 71 is provided at the top of the oxygen pipe 35, and from which extends the flexible conduit 48 to the compressed oxygen tank or drum 30. The solenoid-operated metering valves 70, 71 may be controlled by a coordinating conventional timer circuit, not shown. Thus, with the pressures and rate of flow from the propane and oxygen sources known or capable of estimation, the timer circuit can be arranged to operate the metering valves to let through propane and oxygen, respectively, in the ratio of one volume of propane to say six volumes of oxygen. As stated hereinabove, it may be estimated that there may be three volumes of air in the bored hole to be mixed with the propane and oxygen, but this is not an essential requirement, and more or substantially less air may be present, it only being essential that the ratio of propane to oxygen be maintained within fairly close approximation.

In this regard, the propane ratio may be increased if hard formations are encountered near the surface, fairly difficult of penetration by sound vibrations, or the oxygen ratio may be increased in formations which are softer and/or excellent carriers of transmitted sound waves.

The detonation of the explosive mixture of propane and oxygen, or of propane oxygen, and air takes place in the space below the closure plate 41 and the bottom of the bored hole 13, (as shown in FIG. 2), in the following manner.

The explosion engineer 43, who has previously supervised the placing of the geophones 19 in their properly surveyed positions, and observed that they were level; and who then has controlled the inflation of the sleeves or packer sections 35 to seal the bored hole 13; and who then has controlled the proportions of pressurized propane or oxygen which have passed downwardly through the respective check valves 44 and 47; now presses the handle of the firing box 42, which discharges a condenser in the box in circuit with the igniter electrodes. whereby there is a spark emitted between the igniter electrodes 72, 73 below the closure plate 41, resulting in the detonation or explosion of the propane-oxygen mixture.

The lowermost sleeve 35a, of the detonator 33, comprises an explosion chamber 74, and as it extends below the housing or casing pipe 34, and is not normally billowed outwardly by compressed air, it extends as a substantial cylinder, as held in shape by a bottom ring 75, as of metal. However, when the explosion occurs the lowermost sleeve 35a is also billowed out to fit against the bore 13 and to compress the bore into a crosssectional configuration, as shown in FIG. 2, corresponding with the cross-sectional configurations of the compressed airpressurized sleeves thereabove.

The explosion is channelized through the opening 76 in the disk or frame ring 75 to pass on downwardly into the cavity 77 of the bored hole 13. If there is any back blast it could act upwardly within the sleeve or packer structure, between the pipe 34 and the lowest sleeve glued junction or bond 69, and tend to rupture the bond. Or it could pass upwardly, if of strength to pass the lower sleeve 350, as the initial compression due to the explosion reduces, and in this case it will tend to decompress, and force the lowermost pressurized sleeve 35 away from the well bore.

However, in this case of an improbably overforceful blast accomplishing these first results, the result is in opposition to further upward blast because of the lower pressurized chamber. Also, in case on a rare occasion further rupture or upward advance could occur, the cumulative resistance of the compressed air, as contacted, is brought in direct opposition to the upward travel of a back blast.

Obviously, since any back blast forces of explosion will encounter increasing resistance, even if they can rupture the lowermost sleeve junction 69 from its glued or otherwise bonded contact with the detonator housing or casing pipe 34, the explosion expends itself in penetrating into the earth. But as the products of combustion from the explosion cannot be liberated with such force as is developed by dynamite, but can move downwardly in the lower part of the bored hole 13 (l4, 15), it follows that the bored hole, with its volume, can act as a channelizer, and at the same time, since there is not enough force generated by the explosion to rupture its walls, the forces liberated by the explosion move off progressively as deeply penetrating vibrations, into the formation generally below the bored hole. In this manner much smoother and more penetrating vibrations are liberated more slowly, but with a greater force, and oflonger duration.

In effect by comparison, dynamite may be compared to a high-speed, low-torque machine, accomplishing shattering of the shothole due to its speed, whereas the explosion of a propane-oxygen mixture, with a cavity or lower bored hole into which it can expand, compares with the action of a lowspeed high-torque machine, not dazzling in accomplishment due to its rapidity, but causing much greater results because of the much greater but slower acting force at its command.

In the panoramic view of FIG. 1, the performance of the in stant invention can be visualized as an operation which differs from conventional procedures in several important particulars. The boreholes l3, l4, and 15 may be to the same depth as the conventional shothole, but there is a decided difference in that the dynamite conventionally employed is placed in the bottom of the shothole, whereas in the instant invention a cavity is left below the detonator 33 into which the explosion ofa hydrocarbon supported by oxygen takes place. The quality of the explosion is such that practically all of its force is directed downwardly and very little goes in an effort to shatter the shothole. On the other hand, in a dynamite explosion it is inherently necessary that much of the explosive energy expands itself shattering out of its narrow confines and breaking away the immediate formation therearound including therebelow to provide space for the expansion of the liberated gases.

In the case of the instant invention the explosion penetrates with evenly propagated waves inclined to greater and smoother undulations which are correspondingly reflected from any layer as the illustrated limestone layer A, or the limestone layer B in FIG. 1.

The manner in which the recorded vibrations appear after development is shown in FIG. 1 where, after the shot moment of explosion, first time arrivals reflected from upper layers are followed by the reflections from the upper limestone layer A, and reflections from the lower limestone layer B follow thereafter. On such a developed tape or roll, time is the ordinate and amplitude is the abscissa.

An observation of the sectional elevation comprised by the lower part of FIG. 1 indicates that when the second bored hole 14 is ready to be employed, with the detonator 33 in place and connected and the geophones l9 moved to an alignment therefrom, several of the geophones will receive B-type reflections as influenced by the oil pool" indicated in the lower central part of the figure.

The invention is adapted for use in low, damp, coastal countries, where water is encountered slightly below the surface, as shown in FIG. 8. In this case an adapter flange is connected to the ring 75 by flathead machine screws 81, and a plastic, as a neoprene sleeve 84 is connected therebelow, as by means of its upper flange 82 being connected by bolts 83 to the adapter flange 80. The sleeve 84 is of sufficient length to supply space 86 into which the explosion may develop, and extends downwardly into the water, with, or partially liquid matter filling the bored hole 13. In order to relieve the explosion, a relief valve 87 is connected to a suitable flange 88 on the lower end ofthe neoprene sleeve 84,

The invention permits facile comparison of results since the gas volumes may be accurately measured, as well as the cavity space below the detonator, so that a succession of identical volume gas explosions in a borehole l3 imparts practically identical shock waves to the respectively correspondingly located various geophone casings 19 along the earth's surface. Also, for comparison, by varying the gas volume in the bore hole, the explosion imparts seismic shock waves of different character and frequency through the earth to the said seismic detector stations.

Also a number of bored holes similarly arranged with detonator similarly placed, may be exploded simultaneously with the same charges, and a summation of the generated seismic shock waves imparted to the comparably disposed geophone cases.

Also the apparatus may be fitted into a plurality of bored holes of any array, and the plurality fired in a sequence of from I to ID milliseconds apart, whereby the magnitude of the seismic shock waves is effectively intensified, while the earth 5 medium sums the seismic waves which are of in-phase character before arrival at the seismic detector stations (geophone casings 19).

The geophone casings 19, containing a plurality of geophones 62 comparably disposed on a suspended support plate 55 within a padded or buffed casing results in substantial uniformity of reception of comparable waves, and in effect sums the seismic shock waves created by the gas explosions in the bore holes. Also extraneous out-of-phase waves and horizontal shear and stress waves are eliminated, so that the summation is that of nearly vertically reflected shock waves. This summation of the seismic shock waves created by the gas explosions in the boreholes and summed by the sets of geophones in the casings may be recorded by any of conventional modern methods, digital, magnetic, mechanical, or photographical.

An observation of the sectional elevation comprised by the lower part of FIG. 1 indicates that when the second bored hole 14 is ready to be employed, with the detonator 33 in place and connected and the geophones l9 moved to an alignment therefrom, several of the geophones will receive B-type reflections as influenced by the oil pool" indicated in the lower central part of the figure.

The second copending part of this application is brought forward hereinunder as follows:

A detonator or gun 33 is shown in FIG. 9 disposed in a bored hole 13', the detonator including upwardly a pipe housing 34' and therebelow an explosion barrel 90, with a closure plate 91 being disposed between the lower flange 34a of the pipe housing 34' and the upper flange 90a of the explosion barrel 90; the pipe housing 34', closure plate 91 and the explosion barrel 90 being assembled conventionally by nuts and bolts through suitable bolt circle holes, not shown. A single packer 35 is shown in full lines to be employed to fix the detonator 33' in position in the borehole 13', the packer being of rubber and the like and being disposed around the pipe housing 34 and inflated by compressed air passed by means of a conduit pipe 32 downwardly through a cap plate 38' into the upper part of the pipe housing 34 to communicate with the interior of the packer 35 thus to fill an interior space 37 therewithin created as the packer is bowed outwardly between its upper and lower anchorages against the underside of the cap plate 38' and against the upper surface of the pipe-housing flange 34a.

1n the event double assurance of the detonator 33 being firmly fixed in the well bore is desired, a second packer or flexible sleeve 35a, as of rubber, may be disposed with its upper end anchored against the top flange of the explosion barrel 90 and with the lower end of the packer 35a being anchored by a suitable flange or anchor ring, not shown, but disposed at a spaced distance below the upper anchorage of the packer 35a and around the explosion barrel 90. In this event a passage or communication port 92 is provided through the pipe-housing flange 34a, through the closure plate 91, and through the explosion barrel upper flange 90a. In such case the passage 92 is plugged when only a single packer 35' is to be used and unplugged when the second or lower packer 35a is to be employed.

The closure plate 91 has assembled therewith a vent line check valve 93 including an upper inlet pipe or nipple which is threaded upwardly through the closure plate 91 from the underside to extend thereabove and to have a conventional snapon coupling 94a connected thereonto. Also, the closure plate 91 has threaded upwardly therethrough the terminal portion 95b of an igniter 40', such portion including the spark plug 95 which ignites the explosive charge to be hereinbelow described, the portion 95b having an insulative coupling 95a connected onto the upper end thereof. Also, the closure plate 91 has the inlet nipple or pipe of a propane line check valve 47' threaded upwardly therethrough, the check valve 47 being of the type having its valve element yieldably urged seated upwardly, the inlet pipe or nipple extending above the closure plate 91 and having a snap-on type coupling 94!: connected thereonto. Also, an oxygen line check valve 44 has an inlet pipe or nipple threaded upwardly through the closure plate 91, the check valve 44 having its valve element yieldably urged seated upwardly, and the inlet pipe or nipple having a snap-on type coupling 94c connected thereonto.

With the closure plate 91 thus assembled, it is only necessary to pass a vent conduit 96 through the cap plate 38' for engagement with the snap-on type coupling 94a; to pass the electrical conduit or igniter 40' through the cap plate 38 for connection to the insulative coupling 95a and carry the conductor wires 39a, 39b therefrom through the coupling 95a to the spark plug 95; to pass a propane conduit or pipe 36a through the cap 38 for connection to the snap-on type coupling 94b, and to pass an oxygen conduit 36]; through the cap plate 38' for connection to the snap-on type coupling 940; then the cap plate 38' may be connected on top of the pipe housing 34', and the upper part of the detonator 33' will be considered completely assembled.

The lower part of the detonator explosion barrel 90 comprises a lower flange 97, and such flange 97 has a counterbore 98 in the underside thereof. As its lowermost element the detonator 33' provides a deflector 100 of substantially the inner diameter of the explosion barrel 90 and such deflector has a flange 99 as the upper element thereof for connection to the explosion barrel flange 97. The flange 99 is counterbored to provide a recess 101 therein which is complementary to the recess 98 in the flange 97 whereby to receive therein the seat providing valve plate 112 of a valve 102, such valve plate 112 being countersunk from the underside to provide a tapered valve seat 103 with the slope of the taper, as shown in FIG. 10, being approximately 60.

The valve plate 112 has a central bore 104 therethrough of the same diameter as a corresponding bore 105 through the valve element 106 so that the shank of a bolt 107 may be passed through both valve plate 1 12 and valve element 106 to extend therebelow. The shank of the bolt 107 passes through a series of compressible or deformable rubber or neoprene disks 108 above a washer 109, the lower end of the bolt 107 extending through retaining nuts a and 110b which may be threaded upon the lower end of the bolt 107 to assemble the valve element 106, the compressible disk 108, the washer 109 and the nuts 110a and 110b together in manner that the valve element 106 is yieldably urged firmly seated against the valve seat 103.

Finally, a series of ports or bores 11] are provided in the valve plate 112, equally, angularly spaced apart and equidistant outwardly from the center of the valve plate 112, and thus disposed on a bolt circle, which, as shown in FIG. 10, is nearer the periphery of the valve plate 112 than it is to the center thereof. By this construction the valve 102 is provided with a valve element 106 which may be adjustably and experimentally tensioned in manner to open responsive to explosions within the explosion barrel 90 as such explosions achieve a predetermined intensity.

Above the cap plate 38' as shown in FIG. 9, a solenoidoperated valve 113 is provided at the top of the packer-inflating conduit 32, and from this valve 113 a conduit 31 leads to a compressor corresponding with the compressor 29 shown in FIG. 1. Also, at the top of the vent conduit 96 a solenoidoperated valve 114 is provided through which the products of explosion may be selectively vented, from within the explosion barrel 90, to the atmosphere.

Also, at the top of the propane conduit 36a a solenoidoperated metering valve 115 is provided to control the passage of propane gas which enters the valve through a conduit 450, the conduit 450 corresponding with the conduit 45 as shown in FIG. 1, through which propane is supplied from a propane tank or reservoir corresponding with the reservoir 28 shown on the truck 27.

Also, at the top of the oxygen conduit 36b a solenoidoperated metering valve 116 is provided to control the passage of oxygen from a conduit 48a, the conduit 48a extending to an oxygen drum corresponding with the oxygen drum 29 shown on the truck 27 in FIG. 1.

Additionally, at the top of the electrical conduit or igniter 40' an electrical outlet 117 may be installed from which insulated conductors 39a and 39b may extend to connect respectively to the positive side 121 and the negative side 122 of a source ofelectrical power.

A firing box 42, corresponding with the firing box 42 shown in FIG. 1, may be provided to control the operation of the improved apparatus shown in FIGS. 9-11, the box 42' having a timer 118 therein which may be actuated by an electrical motor, not shown, (or by a mechanical clock or other suitable device).

A positive side lead 123 extends from the powerline positive side 12] through a pushbutton-type switch to the timer drive, while a negative side lead 124 extends from the opposite side of the timer drive to the power line negative side 122; the pushbutton switch 125 being of the type to actuate the timer for a predetermined cycle whereafter the circuit is-broken.

The revolving timer disk has a cam 126 installed thereon, and right after the timer is started this cam begins maintaining contacts 127 closed through which a positive side conductor 129 carries current to two negative side conductors 130a and 130b, as circuit is completed to these negative side conductors by a double pole, double throw switch 128 which is closed by the cam 126 closing the contacts 127. The electrical conductor 130a includes in series therewith the coil which operates the solenoid of the oxygen-metering valve 116, and the electrical conductor 13% has in series therewith the coil which operates the solenoid of the propane-metering valve 115.

The cam 126 may be adjusted as to the length of are which it subtends, thereby to maintain the contacts 127 closed for selective predetermined time intervals corresponding with the time determined for a proper explosive charge or mixture of propane and oxygen to be delivered into the explosion barrel 90, as metered by the respective propane and oxygen metering valves 115, 116.

As shown in FIG. 9, a firing contact point 131 is provided on the revolving disk of the timer 118, and as the disk moves in counterclockwise direction the firing point 131 is disposed to instantaneously close and then break the firing contacts 132 just after the cam 126 has rotated past the contacts 127. The contacts 132, when closed, electrically connect a positive side conductor 133 to carry current to the aforesaid electrical con ductor 39a to the electrical outlet 117 and through the igniter 40' to one side of the gap of the spark plug 95; the other side of the spark plug 95 being connected by means of the aforesaid electrical conductor 39b which passes up the igniter 40' and out through the outlet 117 to the power line negative side 122.

The revolving disk of the timer 118 also carries a cam 134 which is disposed to close contacts 135 at a predetermined time interval after the closing and breaking of the contacts 132. A positive side conductor 137 carries current through the contacts 135, when closed, and circuit is continued through a negative side conductor 138, which includes the coil of the solenoid of the vent valve 114, to the power line negative side 122. As in the case of the cam 126 the cam 134 is adjustable as to the length of are it subtends and thus the length of time that the contacts 135 are closed may be predetermined, and thereby the length of time the vent valve 114 may leave open the vent conduit 96 to vent the explosion chamber 150 of the explosion barrel 90 may be experimentally determined.

It is not necessary that the timer 118 control the opening and closing of the packer-inflating valve 113 since the setting of the packer 35' is a distinct preliminary operation. However, for convenience, a switch 140 may be provided in the firing box 42 and upon holding this switch pressed inwardly, circuit may be completed between positive side conductor 141 from the powerline positive side 121, by way ofa negative side conductor 142 to open the solenoid-operated valve 113, whereby compressed air from a compressor corresponding with the compressor shown on the truck 27 in FIG. 1, may deliver compressed air through the conduit 31 and through the open valve 113, and down the conduit 32, to set the packer as aforesaid.

In cases, as for instance during experimentation, it may be desired to use the timer 118. Thus a manually operated switch 143 is provided in the firing box 42 and connected to actuate the double-throw switch 128 to close circuit to the contacts 127 and thus set in motion the flow of propane and oxygen to pass through the respective open valves 115, 116, conduits 36a, 36b and check valves 47, 44' to admit the mixture of propane and oxygen into the explosion barrel expansion chamber 150. Also, a switch 144 may be provided to be operated manually to close the contacts 132 thereby to fire the spark plug 95. Also, a switch 145 may be provided in the firing box 42 to be manipulated to hold the contacts 135 closed thereby actuating the vent valve 114 to permit the venting of the explosion chamber 150 after a blast has been detonated.

Referring now to FIG. 11, a detonator 33' is shown assembled to be discharged under water In this case the pipe housing 34' is shown installed. as in FIG. 9. upon the top of the explosion barrel 90, in which case the opening, not shown, of the conduit 32' through the wall of the housing would be plugged, and the packer 35, shown in FIG. 9, would not be used. Also, the pipe housing 34, as installed, would serve only as a handling means whereby the explosion barrel 90 could be lowered into deeper water. In such case the electrical conductors from the spark plug or igniter, not shown, are indicated as enclosed in a common insulated, flexible cord 120 extending through, and above, the closure cap 38'. Additionally, flexible conduits 36c and 960 are shown extending outwardly from under the closure cap 38, respectively to a propane and oxygen mixing valve, and to a vent valve, these items not shown Optionally, the pipe housing 34 could be wholly omitted and the detonator could serve well or even better for underwater firing, and in this case the electrical cord 120, and the flexible conduits 96a and 360 are indicated in dotted lines as extending outwardly from above the proper couplings, not shown, above the closure plate 91.

In operation, with a detonator packer set in a bored hole, it has been found best to provide an explosion barrel approximately l0 feet long with 5 inches inner diameter, 5%inches outer diameter and thus %-inch wall thickness, and thereby providing an explosion chamber approximately 1.36 cubic feet in volume. In such a detonator the relief valve may best be urged closed by five 2-inch outer diameter by three-fourth inch inner diameter medium rubber disk on the valve stem. For the best charge, oxygen at 50 pounds gauge pressure, and propane at l5 pounds gauge pressure, may be admitted through three-fourth inch pipe size orifices, for a charging period of 1 minute. This charge should develop 10 pounds per square inch pressure when fully mixed in the explosion chamber.

Then, when the explosion charge is almost instantaneously detonated at the end ofa minute of mixing a gas blast pressure some bit in excess of l,400 pounds per square inch is developed within the explosion barrel as the charge is fired by the spark plug. The pressure developed in the explosion chamber is at first substantially above l,400 pounds per square inch, and first falls ofi' to still some bit above l,400 pounds per square inch to some bit below l,400 pounds per square inch during the blast, and the relief valve closes as the pressure within the explosion chamber drops to 250 pounds per square inch. A venting period of substantially no more than 5 seconds has been found adequate to begin almost immediately after ignition. Also, it has been found expedient to employ a timer which will fire approximately l5 gas blasts in say a period of l6minutes to propagate a series of successive energy charges passing downwardly. It has been estimated that the admission of oxygen and propane under pressure aforesaid, will result in a charge propagating waves to travel at say 4,000 ft./sec. if the charge lasts say 20 seconds, whereas, if the charging period lasts for 1 minute at the rate or under pressures aforesaid, the rate of propagation should be approximately 13,000 ft./sec.

In case the propane is admitted in greater ratio than over 2 to l oxygen to propane, so that a richer explosion is obtained, the rate of propagation will be greater, and conversely, if the proportion of oxygen is increased the propagation will be at a reduced speed.

Under the preferred conditions aforesaid, energy or sound waves emitted below the relief valve tend to pass much straighter, or much more vertically downwardly, or with less slant than those waves propagated by dynamite charges, Also, gas blast waves are reflected back with less angle of slant and at greater frequency, as say 40 cycles per second against 20 cycles per second for waves propagated by conventional dynamite charges in the earth.

Also, since the waves travel downwardly with less slant and more at the vertical, the geophones which receive the reflected energy or sound waves back at the earth's surface need not be placed so far away from the source of origin of the blast. Thus the closest ring of geophones may be placed at approximately l,000 feet from the blasthole with the outermost ring of geophones placed approximately 2,600 feet therefrom thus to cover the practical working radial range, which compares against 1,320 feet minimum to approximately I mile or 5,280 feet general maximum for the spacing of geophones which receive conventional dynamite-propagated waves.

Consequently, this invention provides apparatus for propagating sound waves requiring a smaller detecting area at the earths surface and which obtains higher frequency waves as plotted, thereby saving in geophone operating costs and also permitting a finer interpretation of conditions down in the earth from which the waves are reflected back to the surface.

As to waves set off in water rather than by a detonator as packer set in a bored hole, the results can be practically as efficient due to the tendency or propensity for gas blasts propagated waves to pass substantially vertically downwardly so that the depth of water between the bottom of the deflector and the subterranean surface does not retard the rate of passage of the waves or deflect them in any harmful manner. Thus, the plotted results are not beclouded by comparison with gas blast waves which travel entirely downwardly and back upwardly through the earth.

It is also noticeable that the error and interference by the weathered zone or surface layer which often enters into the results obtained by dynamite propagated waves does not enter and interfere with the gas propagated waves of this invention, and to this fact is attributed the higher frequencies and greater uniformity of plots obtained of gas blast propagated waves.

In refinement of the invention it has been found that under certain environment the packer means to seal the blast gun in a bore may not be necessary so that the blast gun may be detonated in a bore corresponding with the bore 13 shown in FIG. 9, with water in the bore extending up to some substantial level around the blast gun to effectuate the equivalent of a seal when the gun is discharged. In such cases the water should stand in ample volume and to ample height above the area of expansion and/or movement of gases liberated from the gun chamber upon discharge, thus to ensure that the water will not be forcefully blasted upwardly out of the bore and with this water seal no such up-blast will occur as long as the bottom of the deflector is disposed at some slight distance, as from 1 to 3 feet, above the bottom of the bore when discharge occurs.

Also it has been discovered that the opening of a vent valve, as the valve 93, shown in FIG. 9, (in the absence ofa purging force or means), may not on occasion be an ample provision to ensure against the accumulation of combustion products in the gun chamber to build up successively after successive explosions. It can be appreciated that if such a buildup of products of combustion can occur, the character or quality of seismic waves propagated downwardly upon successive detonations may fall offin intensity, and thereby tend to affect the records obtained, at least in some degree. Accordingly, as disclosed in FIG. 12, injecting a purging gas, as compressed air, after each detonation, as will be hereinbelow described, can ensure proper evacuation of the gun chamber before each successive charge.

Referring now in detail to FIGS. 12 and 13, the blast gun or detonator 33b includes a pipe housing or upper tube 34b closed by a cap plate or flange 38b; an explosion barrel or tubular chamber 90, with lower flange 34c bolted to an upper flange 91' of the barrel 90, and the lowermost a deflector 100 with upper flange 99 bolted to the lower flange 97 of the barrel 90'. v 1

As in FIGS. 9 and 10, the flanges 97, 99 are complementally recessed to receive the outer annular part ofa valve plate 112 thereinbetween. The valve plate 112 has a central bore 104 therethrough and a bolt circle of ports or bores 111 therethrough. The shank ofa bolt 107 passes through the central bore 104, and downwardly therebelow through neoprene disks or compressible rings 108, the bottom disk v108 seating upon a washer 109. In FIG. 12 such washer 109 is shown held in place by nuts 1100, 110b threaded upon the lower end of the shank of the bolt 107 to lock the rings 108 in compressive assembly with uppermost ring to bear against the under surface of a valve element 106' which normally seats upwardly against a valve seat 103 provided in the underside of the valve plate 112.

By varying the extent on the bolt shank upon which the nuts 1100, 11% are threaded, the tension with which the neoprene disks or rings 108 bear against the underside of the valve element 106' may be varied to regulate the length of time and extent or degree ofopening of the valve element 106 responsive to explosions of various degrees of intensity within the explosion chamber 150.

The explosion in the chamber 91 is effected, as in the previously described gun chambers, by admitting combinations of propane and oxygen, as hereinabove described, to pass down the respective conduits 36a, 36b and into the chamber to mix and to build up pressure within the chamber; then to be detonated by the spark plug 95 which passes through the lower portion 95b of the igniter 40' to spark within the chamber when the igniter circuit is closed. As in the case of the conduits shown in FIG. 9, an insulative coupling a is connected to the upper end of the lower portion 95b of the igniter 40; also, snap-on type couplings 94b and 94c connect the respective propane and oxygen conduits 36a, 36b to the plate 91' above their discharge ends therebelow, through the respective upwardly seating check valves 47', 44' into the combustion space 150.

As shown in FIG. 12, the aforesaid purging gas, to purge the chamber 150 after each explosion, is brought from a source, not shown, as from a compressed air bottle, or from a compressor, as located on the EXPLOSIVES TRUCK shown in FIG. 1, and passes through a conduit 96 downwardly through the cap plate 38b, and through the pipe tube 34b, to be anchored by a snap-on coupling 94a to the closure plate 91 to pass downwardly therethrough to the upwardly seating check valve 93.

correspondingly, as shown in FIG. 9, solenoid-operated valves 114, 115, and 1 16 are provided in the respective purge, propane and oxygen conduits 96', 36a, and 36b. The solenoidoperated purged valve 114 is connected across the power source 121, 122 by a conductor 137, the timer box switch 135 and the conductor 138. Also, the solenoid operated propane valve 115 and the solenoid-operated oxygen valve 116 are connected across the power source 121, 122 by means of the conductor 129, the timer box switch 127, the double pole, double throw switch 128 and the respective conductors b, 130a. Also, an electrical outlet 117 at the top of the igniter 40, is connected across the power source 121, 122 by means ofa conductor 133, the timer box switch 132, and the conductors 39a and 39b.

A timer corresponding with the timer shown in FIG. 9, and located within the firing box 42b, is connected across the power source 121, 122 by means of the conductor 123, pushbutton 125, the timer dial 118 and the conductor 124. An adjustable cam 126, contact point 131, and an adjustable cam 134 are angularly spaced apart around the periphery of the timer dial 118, at selective angular distances apart, and with the cams 126 and 134' adjusted to subtend predetermined arcs in length. Thus, when the pushbutton 125 starts the timer, the cam 126 first closes circuit to charge the chamber with propane and oxygen, then the pointer 131 ignites the charge, and shortly thereafter the cam 134' opens the purge valve 114 to inject purge air into the chamber 150 to purge it,

as will be hereinbelow described.

As handled, the blast gun or detonator 33b is lowered into a bored hole 131) in the earthen formation, corresponding with the bores 13 and I3 hereinabove described, but which may be slightly smaller in diameter since it is not necessary to use packers to seal the bore 13b. However, in this case the bore 13b has water poured therein. Thus the blast gun or detonator 13b may be lowered into the bored hole 13b, as from an A- frame 151 on the rear ofa vehicle 152, a cable 153 being connected into an eyelet in the center of the detonator cap plate 38b, and the cable 153 being handled over a pulley 154 at the peak of the A-frame 151, all as shown for convenience to exaggerated small scale, or diagrammatically, in FIG. 12. Also, the upper tube 34b may be omitted when flexible conduits such as the purge and mixture conduits 96a, 36c shown in dotted lines in FIG. 12, are employed, together with a flexible electrical conductor cord 120 in place of the electrical condulet 40', shown in full lines in FIG. 12. In such case the eyelet 155, to which the handling cable 153 is connected, would be anchored centrally in the top of the closure plate 91.

The small scale view of FIG. tube 34b assembled with the deflector 100 13 discloses the conduit or pipe firing barrel 90 and with the being assembled to the lower end of the firing barrel 90', the reference numerals applied to the respective parts being those shown in FIG. 12. In this case the conduits 36a, 36b, and 96, and the electrical condulet 40' extend above the cap plate 381). Alternately, with the pipe tube 34b omitted, alternative conduits 36c and 96a, and flexible conductor 120 extend above the closure plate 91'.

The firing box 42b, shown in FIG. 12, is equipped in correspondence with the firing box 42' shown in FIG. 9 as to manually operated switches 143, 144, and 145, which can serve in place of the timer 118 to selectively close the respective charging circuits 130a, 130b, the firing circuit 39a, and the purge circuit 133. Also the detonator 33b is constructed in correspondence with the detonator 33 shown in FIGS. 91 1, inclusive, except as hereinabove noted, except for one important feature to be hereinbelow described, and with the additional feature, that, when a pipe tube 34b is used, the lower pipe tube flange 340 is bolted directly to the upper flange 91' of the barrel 90', as by bolts 147 indicated diagrammatically in FIG. 12.

The records obtained with this preferred form of the invention, as improved by the consistency of blasts obtained by the purging step, have been plotted in FIGS. 14 and 15. The location from which these records were obtained is in the Delaware" basin of West Texas, near the New Mexico-Texas state line, with the oil to be discovered lying deeply under the ground.

In the operations resulting in obtaining the records shown in FIGS. 14 and 15, a hole 13b, as shown in FIG. 12, was drilled from the surface into the earth, the hole being approximately feet in depth, or 5 feet more than the length of the blast gun 33b. The hole was filled with water 149 up to a distance of a few feet from the surface, and above the connection to the pipe tube 34b, as shown in FIG. 12. Then the blast gun 33b was lowered into the bored hole 13b, as from the vehicle 152, as aforesaid, and supported by the cable 153 to extend downwardly into the bore 13b to a distance whereby the lower end of the deflector 100' is disposed slightly above the bottom 156 of the bore 131) The fact that there has to between the bottom of the deflector 100' of the hole 13b, can be critical, because if the blast gun 33b is disposed upon detonation in manner that the bottom of the deflector 100 is actually on the bottom 156, or within a very few inches thereof, the waves set in motion upon detonation, at least in part, will not pass on downwardly through the bottom 156, but will be deflected back upwardly, together with some of the products of combustion and liberated gases, with the result that considerable water is blown out of the hole 13b, and also the blast gun 3312 may itself be blown upwardly.

The detonator 33b, shown in FIG. 12, is constructed in correspondence with the detonator 33' shown in FIGS. 9-11, inclusive, as to dimensions and proportions, and operates generally in correspondence with the description of operation described hereinabove. Notably the purge period, substituted herein for the vent period, is of corresponding duration, as say for approximately 5 seconds, more or less, as may be set by the adjustable contact 134'. The important feature, referred to, but not hereinabove described, by which purging is effectuated, comprising a single small diameter bleed hole or passage 148 through the valve element 106, to communicate with one of the port holes 111 in the valve plate or seat 112.

Thus, for say approximately 5 seconds, compressed air from a compressor discharge or from a be some distance, although slight, and the bottom 156 of say one-sixteenth inch provided through the valve element 106', as aforesaid. Thus products of combustion, or unspent and residual gases which have not escaped through the ports 111 by the time the valve element 106' reseats after a blast, will be forced out through the small diameter bleed passage 148.

As a consequence of this purging step, substituted for the aforesaid venting step, the conditions within the barrel at each detonation are substantially the same, so that the explosive gases enter, after each purge, and mix and explode, with the same conditions prevailing as successive purges prevent the buildup of residual products of combustion and gases which otherwise could increasingly affect the quality of successive blasts.

However, if the blast gun 33b is disposed in the water in manner to leave some small depth of water for the detonation to pass through before encountering the bottom of the hole, the blast will be dissipated through the bottom of the bore and into the formation, while the gases of the explosion that bubble upwardly through the water 149 will not be in such force as to splash any water of consequence out at the top of the hole.

While the blast gun 33b was being disposed for detonation, a row of 12 spaced-apart geophones was provided in substantial linear alignment from the bored hole 13b corresponding with the disposition of geophones along one radial line from a single dynamite hole in conventional seismic exploration, where a plurality of dynamite holes are required to obtain a properly interpretative record. The 12 geophones were com nected to oscillograph means extended to a recorder, and the firing box 42b properly wired, was then properly disposed in operative connection to the blast gun 33b, as such was lowered from the vehicle 152 into the bored hole 13b until the lower part of the pipe tube 34b, or upper part of the blast gun, was immersed in the water, the bottom of the deflector being spaced above the bottom 156 of the borehole 13b, as aforesaid.

The blast gun 33b, as thus disposed, was discharged a single time, the firing box button being pressed to close the timer circuit, so that the timer rotates and successively, the cam 126 closes the propane and oxygen delivery circuits to charge the blast gun chambers as aforesaid through the respective upwardly seating check valves 47, 44; the cam point 131 then closing the ignition circuit so that the spark plug 95 ignites the mixed gases in the charged chamber 150, the expanded gases and products of combustion develop pressure to act through the ports 111 to open the bottom of the chamber; the products liberated by the explosion passing through the ports 111 and downwardly by the unseated valve element 106', as it compresses the rubber rings 108.

The deflector 100 directs or channelizes the products of combustion downwardly through the water therewithin, and through the several inches or feet of water that should be left therebelow, and the now expanded gases can pass upwardly around the deflector 100' to bubble through the water 149, which acts in the capacity of an incompressible, but gaspermeable seal. As this begins to occur the waves set in motion by the intensity of the explosion pass through the water below the deflector 100', and downwardly through the bottom 156 of the bore 136 and in this regard it should be repeated that for the best records and most successful operation a satisfactory water travel distance should be left below the deflector 100 and above the bottom 156.

Now, as the force of the explosion dissipates itself in the form of spent gases and residual products of combustion, the valve element 106 can seat against the reduced pressure within the chamber 150.

As the valve element 106' seats, the rotating timer 118 carries the cam 134 to close the purge circuit, thus to admit compressed air into the chamber 150 through the upwardly seating check valve 93 so that the pressurized air may purge or urge out residual spent gases and products of combustion through the small diameter bleed hole or relief passage means 148, Continued rotation of the timer 118 carries the cam 134' obtained from 12 straight or radial line from the blast, with the last bored hole 136, are shown gun pipe tube and correspondingly as in the presented during the prosecution stages of this series of applications.

In particular, by the dynamite charge method geophysical exploration, a plurality of charges are set off at one time from a central core area. Thus two lines of dynamite holes, with a single gun in a single bore, can produce more than an equivalent record.

By comparisions, whereas dynamite charges can cost $100,

approximately $2.00 combined lIl oxygen and propane, need be employed. This factor,

as to crew, operation, maintenance, and time, leads to the estimate that the blast gun method of geophysical exploration can cost, say, $120 for a record survey of say 160 acres, whereas by conventional methods, comparable records can cost approximately $300.00.

Considering that geophysical exploration is the most elTective method so far to obtain indications of the locations of ofa salt dome,

(although many salt domes" do not have oil entrapped thereunder), the vast amount of money spent every year for geophysical exploration can be appreciated. Now comes the applicant and has perfected this invention to reduce the conventional costs of exploration to 40 percent.

The invention may be practiced with various structural above the closure cap 38 at the top of the bored hole 13' may be located elsewhere, as in the proximity of the firing box 42'. Also, the electrical power leads I21 and 122, which are shown diagrammatically in FIG. 9 as being disposed on opposite sides of the sheet, as a matter of fact, may be located together, or even in a common-insulated cord. Thus as a variation of the disclosure of FIG. 9, an

alternate disposition of compressed-air control valve, vent valve, propane control valve and oxygen control valve may be provided adjacent to, or incorporated within the firing box 42. Also, an alternatively disposed electrical outlet or plug may be provided in the firing box 42 in which case a flexible, insulated cord would encase the electrical conductors between this outlet or plug and the outlet 117 above the coupling a. Also, in these alternative conduit could best ternate vent control valve.

Furthermore, a flexible conduit could extend from each of alternative propane and oxygen control valves to the respective couplings 94b and 94c, or, alternative metering valves can receive propane and oxygen, respectively, from respective supply conduits, which both discharge into a common or mixand through a single check valve, not shown, to discharge into the barrel.

Also, the invention may be practiced with various structural modifications, embodiments, variations and changes from the disclosure of FIG. 12, as by locating the valves and the electriutlet shown above the closure cap 381:, and disposing these elements adjacent, or built into the firing box 42b. Thus flexible conduits for the conduction of propane, oxygen and compressed air could extend from solenoid-operated propane, oxygen and compressed-air control valves adjacent, or built into the firing box 42b, respectively, to the couplings 94b, 94c and 94a shown in FIG. 12, or to pipes therefrom which terminate immediately above the closure cap 38b. Also, alternaor adjacent the firing convey the mixture from the mixing chamber to the detonator 38b for proper connection thereat to deliver the mixture into the chamber 150. Also, the firing box 42b could provide the flexibly to the detonator 3817, there to be connected suitably to the coupling 950, as shown in FIG. 12.

As set forth hereinabove, the invention may be practical in various modifications and forms. It is thus not limited to any exact ranges of pressures, time intervals and time cycles, and proportions of charges, nor to the exact structures or sizes and proportions of structures set forth, nor to the exact method steps of practicing the invention hereinabove disclosed, but other pressure ranges, rates of charging, structural proportions, numbers of successive blasts, and special or critical angles, or time cycles are included, as well as such may fall within the broad scope of interpretation claimed for, and merited by, the appended claims.

1. Apparatus emanating energy waves to pass downwardly into the earth, and including a a. detonator providing a b. chambered barrel having a c. normally closed upper end and a d. release valve spaced below said upper end and comprising a l. valve seat extending across said barrel with a 2. stem to extend downwardly therefrom with lower end carrying a 3. base means, a

4. valve element to seat upwardly against said valve seat,

and a e. yieldably upwardly urging means based upon said base means and surrounding said stem and bearing upwardly against said valve element to close said relief valve when the pressure generated by the blast drops off to a predetermined value, said valve element providing f. bleed passage means therethrough whereby to permit exhaust gases to be purged downwardly from said chamber into the water space therebelow after said relief valve has closed following a blast, said detonator providing g. means to admit a fuel and a pressurized combustion-supporting gas into said barrel,

h. means extending into said barrel to ignite the mixture of fuel and combustion-supporting gas, and

i. purge means separate from said means to admit a fuel and a pressurized combustion passage means. 2. Apparatus as claimed in claim 1, in which said detonator includes a pipe tube above bustion-supporting gas, said means to said means to ignite said mixture, conduit means extend, respectively thereabove.

3. Apparatus as claimed in claim 1, which additionally includes a firing box with a timer and operating circuitry, and in which said means to admit a fuel and a combustion-supporting gas and said means to admit a purge gas include solenoid- 4. Apparatus as claimed in claim 1 in which said flexible conduit means extend from said closed upper end of the barrel of the detonator.

5. Apparatus as claimed in claim 1. includes a pipe tube above said barrel, nected to the pipe lowered into, and raised from, the water.

6. Apparatus as claimed in claim 1 in which said detonator from the water, said flexible from said upper end of said barrel.

7. Apparatus as claimed in claim 1, in which said detonator includes a deflector sleeve to be affixed to the lower end of said barrel below said relief valve. 

1. Apparatus emanating energy waves to pass downwardly into the earth, and including a a. detonator providing a b. chambered barrel having a c. normally closed upper end and a d. release valve spaced below said upper end and comprising a
 1. valve seat extending across said barrel with a
 2. stem to extend downwardly therefrom with lower end carrying a
 3. base means, a
 4. valve element to seat upwardly against said valve seat, and a e. yieldably upwardly urging means based upon said base means and surrounding said stem and bearing upwardly against said valve element to close said relief valve when the pressure generated by the blast drops off to a predetermined value, said valve element providing f. bleed passage means therethrough whereby to permit exhaust gases to be purged downwardly from said chamber into the water space therebelow after said relief valve has closed following a blast, said detonator providing g. means to admit a fuel and a pressurized combustion-supporting gas into said barrel, h. means extending into said barrel to ignite the mixture of fuel and combustion-supporting gas, and i. purge means separate from said means to admit a fuel and a pressurized combustion gas and to admit a purge gas into the uppermost part of said chamber after said relief valve closes to purge said barrel through said bleed passage means.
 2. stem to extend downwardly therefrom with lower end carrying a
 2. Apparatus as claimed in claim 1, in which said detonator includes a pipe tube above said barrel through which upwardly extend said means to admit a fuel and a pressurized combustion-supporting gas, said means to admit a purge gas, and said means to ignite said mixture, and from which said flexible conduit means extend, respectively thereabove.
 3. Apparatus as claimed in claim 1, which additionally includes a firing box with a timer and operating circuitry, and in which said means to admit a fuel and a combustion-supporting gas and said means to admit a purge gas include solenoid-operated valve means, said timer and said circuitry being operable successively for solenoid operation of said fuel and said combustion-supporting valve means, to open and close said ignition means, and to open and close said purge valve means.
 3. base means, a
 4. valve element to seat upwardly against said valve seat, and a e. yieldably upwardly urging means based upon said base means and surrounding said stem and bearing upwardly against said valve element to close said relief valve when the pressure generated by the blast drops off to a predetermined value, said valve element providing f. bleed passage means therethrough whereby to permit exhaust gases to be purged downwardly from said chamber into the water space therebelow after said relief valve has closed following a blast, said detonator providing g. means to admit a fuel and a pressurized combustion-supporting gas into said barrel, h. means extending into said barrel to ignite the mixture of fuel and combustion-supporting gas, and i. purge means separate from said means to admit a fuel and a pressurized combustion gas and to admit a purge gas into the uppermost part of said chamber after said relief valve closes to purge said barrel through said bleed passage means.
 4. Apparatus as claimed in claim 1 in which said flexible conduit means extend from said closed upper end of the barrel of the detonator.
 5. Apparatus as claimed in claim 1, in which said detonator includes a pipe tube above said barrel, and cable means connected to the pipe tube by which said detonator may be lowered into, and raised from, the water.
 6. Apparatus as claimed in claim 1 in which said detonator includes cable means connected to the upper end of said barrel, by which said detonator may be lowered into and rAised from the water, said flexible conduit means also extending from said upper end of said barrel.
 7. Apparatus as claimed in claim 1, in which said detonator includes a deflector sleeve to be affixed to the lower end of said barrel below said relief valve. 